The Farm Bureau's statistic, because it's based on a ratio, also doesn't distinguish the difference between the size of farms, what crops a farmer grows (and whether the farmer grows crops or raises livestock) or the method of farming that's being done.

First, let's look at farm size. You'd think that the larger the farming operation, the more people that farm feeds, right? But bigger acreage doesn't necessarily translate into bigger contribution.

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Of all the 915 million acres being farmed across America, the average American farm is 434 acres, which is a modestly sized farm. Farms aren't considered large until their acreage is at least 1,000 acres (with annual sales between $250,000 and $499,999 — sales larger than $500,000 or more are considered very large farms). Small farms average 231 acres (and very small farms are nine acres or less), and it's these small farms that dominate the American farming landscape — as many as 88 percent of U.S. farms are small, with annual sales less than $250,000 [source: USDA].

And it's the small and moderately sized farms that end up providing more food for people to eat than do the large farms. How? It's a phenomenon experts call the inverse farm size-productivity relationship: Small farms in the U.S. and around the world are more likely to focus their efforts on actually producing food — crops or livestock — for humans to eat, whereas large farms are often more likely to be large-scale operations focused on producing to-be-exported commodities or crops not intended as edible (such as corn for biofuels or soybeans for animal feed). And because of that, farmers of small farms tend to contribute more food for people to eat.

What agricultural products a farm works with and the methods a farmer uses also matter when it comes to the potential number of people that year's yield can feed.